Eldorado Canyon State Park preserves a truly golden section of the Rocky Mountain Foothills near Boulder, Colorado. Its pointed cliffs framing South Boulder Creek are a playground for climbers. Hikers have a lot to enjoy as well, like Rattlesnake Gulch Trail, which is scenic and attraction-packed, covering 3.8 miles on a lollipop loop. The hike takes a moderate route up the side of Eldorado Canyon to the Crags Hotel Site, the fading ruins of a more-than-century old resort. Above that, a loop rises to bigger views from the side of Eldorado Mountain. Continental Divide Overlook provides the hike’s grandest panorama of peaks along America’s great watershed separator. The entire hike has 985 feet of elevation change, but those looking to dispense a little less effort can turn around at Continental Divide Overlook for a 3-mile round trip hike with 725 feet of elevation change.

Enter the park from the tiny resort town of Eldorado Springs and drive up an impressive canyon between steep cliffs of tan and orange rock. Find Rattlesnake Gulch Trailhead parking area on the left side of Eldorado Springs Drive, 0.6 miles from the park entrance. Examine a kiosk with a map and description of the hike before beginning up Fowler Trail, which connects to Rattlesnake Gulch Trail after 1/8 of a mile. This wide dirt trail heads east, in the opposite direction that you drove in, gradually rising above the road and South Boulder Creek. Don’t be alarmed by the fake rattlesnake placed on an early boulder, but do be cautions if you encounter a real one.

Enjoy views across Eldorado Canyon as you approach the well-marked junction with Rattlesnake Gulch Trail. Turn right to ascend to the west, doubling back on Fowler Trail. This trail is steeper, but the hike remains moderate and the grade never becomes too aggressive. The wide rocky trail curves to the left along a plunging exposed slope to enter Rattlesnake Gulch, a side canyon off Eldorado Canyon that has more tapered terrain than the vertical cliffs on the north side of the canyon. Topping off the dramatic ridge across the canyon is Shirt Tail Peak, which rises to 7,240 feet. Pause to take in this view and then proceed up the trail into Rattlesnake Gulch.

Shirt Tail Peak across the canyon from Rattlesnake Gulch Trail

At 0.3 miles above the Fowler Trail junction, come to a wooden bridge crossing the gulch. Walk to the other side and embark on a pair of long switchbacks that follow the route of an old road. Ascend through a mixed forest, catching views out the bottom of Eldorado Canyon toward the grassland and lakes to the east. The canyon’s tallest ridge is on the north side, taking a jagged course up to Shirt Tail Peak. You’ll also see a formation called The Bastille, which rises steeply over the south side like a fortification at the entry of Eldorado Canyon.

The trail levels out after 1.2 miles as you approach the site of Crags Hotel. Step up to an information panel marking the grounds of an old hotel that was built on a landing that extends into the canyon. The hotel only operated from 1908 to 1912, when it was destroyed by fire. The panel explains that:

Archaeologists who studied this site discovered significant artifacts of Colorado history. For instance, the rock wall remains provide one of the best-preserved examples of retaining walls used in this era. It remains a mystery whether arson or nature caused the Crags Hotel fire.

Guests could arrive at the hotel by driving up Crags Boulevard (which is now Rattlesnake Gulch Trail), via a funicular inline tram that rose from the canyon floor, or via Moffat Railroad, which is now the Denver and Rio Grande Railroad that crosses the mountainside above.

A path out on the Crags Hotel Site

Leave the trail here to walk down a path on a grass-lined path to discover small brick ruins that remain from Crags Hotel. After exploring, return to the info panel and walk a few steps farther up the trail to a split at the start of the loop. If you choose to turn left, that will give you a steep route to the high point of the loop. The branch to the right takes a more gradual course around the loop, heading first to Continental Divide Overlook. Stay to the right through the junction to reach the hike’s premier vista and enjoy a gentler grade.

Easing up through a dense forest of firs and a few aspens, the trail curves to the right and comes up to a junction, a quarter mile from the hotel site. Bear right to walk 0.05 miles out to Continental Divide Overlook. This spot hosts a pair of benches with panoramic views over Eldorado Canyon State Park. Take in the hike’s grandest perspective over Eldorado Canyon, which feels like the culmination of the views you’ve enjoyed to this point. Turn to the left to look out over green ridges forming uneven rows beyond the canyon. Farthest to the west, you’ll catch sight of America’s hydrological divide, the 12,000-foot mountains forming the backbone of the Continual Divide.

If you turned around at Continental Divide Overlook, it would be a 3-mile round trip hike with 725 feet of elevation change. The views over the next part of Rattlesnake Gulch Trail don’t get any bigger, but the trail does have more to offer. To complete the loop, return to the nearby junction and turn right to resume the ascent.

After another 1/8 of a mile, a path appears on the right rising to a saddle on an adjacent ridge. The junction is unmarked, but if you take this short path, you will quickly discover a bonus view over a fir and aspen-covered canyon to the southwest framed by Scar Top Mountain and Crescent Mountain. Look to the left to see a railroad tunnel in the side of Eldorado Mountain.

A pine-covered canyon below the unofficial viewpoint

Return to Rattlesnake Gulch Trail and continue hiking uphill. The wide dirt trail passes through a shaded forest dominated by firs. Eventually, the trail curves around the upper slopes of Rattlesnake Gulch, where the climbing wanes. Grab views over Eldorado Canyon and the area you hiked up earlier. Look across the gulch toward a railroad tunnel through the side of Eldorado Mountain. The trail heads toward this railroad line, which cuts across the opposing ridge. As you get closer to the tracks, the trail tilts downhill and comes to a junction, 2.2 miles from the start. To the right, a closed trail leads to the railroad tracks in an area that is closed to the public. Turn left to descend to the Crags Hotel Site.

Denver and Rio Grande Railroad crosses Eldorado Mountain

In the next 0.4 miles, the trail drops over 300 feet. Hike down through a mixed forest with intermittent canyon views. Return to the junction by the Crags Hotel Site after 2.6 miles of hiking and turn right to retrace your steps down the initial 1.2 miles of trail to finish out the lollipop loop. Hike down the switchbacks, across the bridge, and through the junction with Fowler Trail to return to the trailhead. You’ll be facing out from the mountain on the hike down, making it easy to gaze out over the canyon.

A view down Rattlesnake Gulch Trail in Eldorado Canyon

Rattlesnake Gulch Trail is 3.8 miles round trip with 985 feet of elevation change (potentially reduced to 3 miles round trip with 725 feet of elevation change by turning back at Continental Divide Overlook).

In additional to hikers, the trail is open to dogs and mountain bikes. Eldorado Canyon State Park has an $8 entrance fee per vehicle (as of 2016). The park can become very crowded on weekends and even fill completely. Eldorado Canyon State Park only has parking for around 220 vehicles. When all the parking spaces are full, additional vehicles are denied entry. Less than a dozen vehicles can fit at the trailhead itself, so you may have to walk a short distance to the start of the hike from other parking areas. The road through Eldorado Springs just outside the park is privately owned and public parking along the road is prohibited. Those who can find outside parking may enter the park for a $3.00 per person walk-in fee. For a free option, visitors can make their way into the park over the other end of Fowler Trail, extending the hike by nearly 4 miles round trip.

South Boulder Creek in Eldorado Canyon

To get to the trailhead: From Denver, take Interstate 25 north to exit 217A for Route 36, which heads northwest toward Boulder. After 13 miles on Route 36, take the McCaslin Boulevard Exit toward Route 170 (signs for Superior and Louisville). At the end of the ramp, turn left on McCaslin Boulevard. Cross over Route 36 and make the first right onto Marshall Road (signs for Route 170). Drive 3.7 miles and make a sharp left to stay on Route 170 and approach an intersection with Route 93. Cross the intersection, go through a turn to the left and drive another 3 miles on Route 170 (El Dorado Springs Drive) to the park entrance, passing through Eldorado Springs.

From Boulder, drive south on Route 93 for approximately 5 miles. At the intersection with Route 170 (Eldorado Springs Drive), turn right and drive 3.1 miles to the park entrance.

Inside the park, drive another 0.6 miles up the unpaved park road to the trailhead, which will be on the left. If the trailhead parking is full, drive another tenth of a mile to a bridge over South Boulder Creek and find additional parking around a picnic area.

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